A variety of overhead (electrical) power transmission conductors is known in the art, including those having wires (e.g., aluminum wires, copper wires, aluminum alloy wires, and copper alloy wires) stranded around a core comprising, for example, steel wires or aluminum matrix composite wires (e.g., alpha alumina fibers in an aluminum or aluminum alloy (e.g., up to 2 percent by weight copper)).
Typically, the same overhead electrical power transmission conductor construction is used in a single tension section between dead-end towers, although combinations of constructions may be encountered when a tension section is repaired.
Due to the relatively high or higher cost of many overhead electrical power transmission conductors that are alternatives to the traditional steel-cored overhead electrical power transmission conductors, it is desirable to be able to use the higher cost overhead electrical power transmission conductors in selected areas of a tension section between dead-end towers. In another aspect, it is desirable to be able to have the construction flexibility to use at least two different overhead electrical power transmission conductors in a tension section between dead-end towers.
In another aspect, many overhead power transmission lines have specially designed tension sections such as long span crossings, segments that are specially designed to span obstacles such as rivers. As electrical load increases on these transmission lines, these long span crossings can become “thermal bottlenecks”. That is, the long span crossings may constrain the current allowed to flow through the transmission line because as current flow increases, the long span crossing conductors heat up, elongate from thermal expansion, and sag to the maximum allowed, giving a minimum clearance below the crossing spans. It is often desirable to increase the current carrying capacity of these long span crossings. It may also be desirable to decrease the sag of a crossing span (also referred to as “limiting span”) to allow more clearance, while maintaining the existing current carrying capacity. Also, it may be desirable to reduce the structural loads imposed on either the structures or conductor by severe weather.